The Arduino Pro Mini is a great alternative to a full sized Uno or Mega when you have a small space you want to fit an Arduino into or for when you’re ready to make that project permanent.
It’s got all the same features of an Uno at a fraction of the size(18x33mm) and cost, unfortunately that means that due to the lack of space there is no USB programmer on board and you have to use a separate USB to Serial adapter to program it.
On the bright side if you own another Arduino which chances are you do then you can program a Pro Mini with that very easily. For this post I’m using an Arduino Uno but you can also use a Mega, Mini or Leonardo to upload code to it.
Here is a diagram of how to connect your boards with a 5v version pro mini
EDIT: There are some versions of this that don’t have the DDcduino name on the silk screen but are exactly the same, all links to the DDcduino will now link to the cheaper unbranded version.
The DCcduino Uno is a popular Arduino Uno r3 pin and feature compatible clone with a few differences
The board comes with extra pads next to the standard headers so you can add yourself a second row of female headers and it also includes 12 pads not available on the standard Arduino Uno that allow you to solder in headers giving you extra RX/TX, SCL/SDA, 3.3v/5v, and GND locations which are really useful if you’re using a lot of pins.